A conventional system interconnection inverter has been disclosed, for example, in Patent Document 1. In this system interconnection inverter, a step-up converter, to which DC power is input, is connected to an inverter formed of a switching element in a full-bridge configuration via an interstage capacitor, and an output of the inverter is connected to the AC power system via a filter. The system interconnection inverter includes an inverter protector that stops oscillation operation of the step-up converter and the inverter when overvoltage or overcurrent occurs inside the system interconnection inverter, and a capacitor discharger that discharges accumulated charges of an output capacitor equipped in the filter, based on the output of the inverter protector.
Furthermore, a conventional protection circuit for a DC power supply line has been disclosed, for example, in Patent Document 2. In this protection circuit, when electric current supplied from a DC power supply circuit to a load circuit abnormally increases, an overcurrent and overheat protection element inserted in the DC power supply line is tripped (made to take a protective action), to interrupt the electric current flowing in the load circuit, thereby protecting the load circuit. In this protection circuit, a fuse and the like can be omitted, and when a fault is restored, the DC power supply line can be automatically restored.
Patent Document 1: Japanese Patent Application Laid-Open No. 2001-186664
Patent Document 2: Japanese Patent Application Laid-Open No. H11-196527